It is desirable to provide an angiographic image showing a stent or other interventional instrument with precision and good visibility to enable evaluation of stent placement. The location and inflation status of a stent are of particular interest. A stent consists of a mesh of fine wires. Further, for the visualisation of stents during placement usually an X-ray based angiographic system is used. Displaying stent struts is a challenge when a patient is large and/or steep imaging angles are involved. Quality of images identifying stent location provided by known systems is typically limited because of reduced CNR (Contrast to Noise Ratio), for example. Known systems also lack reliability in detection of balloon marker spheres which are X-ray radio-opaque spheres located at a distal and proximal end of a stent deployment balloon, for example. Further, high contrast objects (like clips, guide wire tips, leads, sternal wires, as illustrated in FIG. 1) may lead to false detection of marker spheres. A system according to invention principles addresses these deficiencies and related problems.